Conventionally, barcode printing technologies and barcode decoding technologies are widely used. According to the barcode printing technologies, a barcode is printed on a printing medium such as paper. According to the barcode decoding technologies, a printed barcode is read by an image capturing device such as a scanner or a camera, and the read barcode is decoded.
Various kinds of data embedding technologies are also widely used. These data embedding technologies include technologies of embedding data having the form of a two-dimensional barcode in an object such as an image or a printed product.
The data embedding technologies also include digital watermark technologies of embedding data difficult to visually recognize in the object. Many of the digital watermark technologies use a method of superimposing a dot pattern on the object.
The data embedding technologies also include technologies of encoding data by the arrangement of graphic patterns formed from uneven line segments. These encoding technologies use a method of superimposing the arrangement of the graphic patterns on the object.
A barcode or two-dimensional barcode printed on a printing medium is noticeable. For this reason, the barcode or two-dimensional barcode may spoil the appearance of the printed product.
A digital watermark embedded in an object, for example, a printed product as a dot pattern may also spoil the appearance of the printed product due to the following reason. To extract the dot pattern (that is, digital watermark) from the printed product, the printed product is captured by a camera in general. If defocusing or camera shake occurs at the time of capturing, the image may degrade, and the dot pattern may disappear from the image. To prevent this, the dot pattern needs to be printed so large and clear as not to disappear from the image. For this reason, the digital watermark that should be difficult to visually recognize becomes noticeable, and the confidentiality and appearance may be spoiled. This also applies to a printed product on which the arrangement of graphic patterns is superimposed. The reason is as follows. To extract the arrangement of graphic patterns from the printed product on which the arrangement of graphic patterns are superimposed, each graphic pattern needs to be printed so large and clear as not to disappear in the process of printing and capturing.
It is an object of the present invention to provide an apparatus and method for embedding data in an object and an apparatus and method for extracting embedded data, which can implement data embedding that attains an excellent confidentiality without spoiling the appearance.